1 Purpose
2 Scope
3 Definitions
4 References
5 The Design Problem
6 Ampacity
6.1 Heat Balance
6.2 Conductor Temperature Limits
6.3 Ampacity Tables
7 Corona and Radio Influence
7.1 Conductor Selection
7.2 Hardware Specifications
8 Conductor Vibration
8.1 Natural Frequency
8.2 Driving Functions
8.3 Damping
9 Conductor Gravitational Forces
9.1 Conductor
9.2 Damping Material
9.3 Ice
9.4 Concentrated Masses
10 Conductor Wind Forces
10.1 Drag Coefficient, CD
10.2 Height and Exposure Factor K2
10.3 Gust Factors, GF
11 Conductor Short-Circuit-Current Forces
11.1 Classical Equation
11.2 Decrement Factor
11.3 Mounting Structure Flexibility
11.4 Corner and End Effects
12 Conductor Strength Considerations
12.1 Vertical Deflection
12.2 Conductor Fiber Stress
12.3 Maximum Allowable Span Length
13 Insulator Strength Considerations
13.1 Insulator Cantilever Forces
13.2 Insulator Force Overload Factors
13.3 Minimum Insulator Cantilever Strength
14 Conductor Thermal Expansion Considerations
14.1 Thermal Loads
14.2 Expansion Fittings
15 Bibliography
Figure
Fig 1 Design Process for Horizontal Bus
Fig 2 General Loading Map Showing Territorial Division
of the United States With Respect to Loading of
Overhead Lines
Fig 3 Basic Wind Speed-Miles Per Hour (mi/h), Annual Extreme
Fastest-Mile Speed 30 ft Above Ground, 50 yr Mean
Recurrence Interval
Fig 4 Kf for Various Types of Single-Phase Mounting Structures
Fig 5 Vertically Mounted Insulator Cantilever Forces
Fig 6 Horizontally Mounted Insulator Cantilever Forces
TABLES
Table 1 Drag Coefficients for Structural Shapes
Table 2 Constant for Calculating Short-Circuit-Current
Forces
Table 3 Modulus of Elasticity E for Common-Conductor Alloys
Table 4 Allowable Stresses for Common-Conductor Materials
Table 5 Effective Bus Span Length LE Supported by Insulator
APPENDIXES
Appendix A Letter Symbols for Quantities
Appendix B Bus-Conductor Ampacity
Appendix C Thermal Considerations for Outdoor Bus-Conductor
Design
Appendix D Calculation of Surface Voltage Gradient
Appendix E Mechanical Forces on Current-Carrying Conductors
APPENDIX D FIGURES
Fig D1 Allowable Surface Voltage Gradient for Equal RI
Generation Under Standard Conditions Versus Bus
Diameter
APPENDIX E FIGURES
Fig 1 Conductor Arrangements-Special Cases
Fig 2 Skewed Conductors
Fig 3 Skewed Conductors-Reference Axes and Dimensions
Fig 4 Direction of Forces-Special Cases
Fig 5 Direction of Forces-Skewed Conductors
Fig 6 Skewed Conductors-B < 90DEG, x and m positive
Fig 7 Skewed Conductors-B < 90DEG, x positive, m negative
Fig 8 Skewed Conductors-B < 90DEG, x negative, m positive
Fig 9 Skewed Conductors-Numerical Example
Fig 10 Distribution of Mechanical Forces on Skewed
Conductors for Various Angles of Cross-Over
Fig 11 70DEG Cross-Over
Fig 12 Orthogonal Components of Mechanical Forces on
Conductors With 70DEG Cross-Over
Fig 13 Short Parallel Conductors
Fig 14 End of Long Parallel Conductor
Fig 15 90DEG Cross-Over
Fig 16 90DEG Bend
Fig 17 Any Angle in a Plane < 90DEG
Fig 18 Any Angle in a Plane > 90DEG, m Negative
Fig 19 Angle between Conductor and Direction of Magnetic Flux
Fig 20 Direction of Mechanical Force
APPENDIX TABLES
Table B1 Single Aluminium Rectangular Bar AC Ampacity, With
Sun (55.0% Conductivity)
Table B2 Single Aluminium Rectangular Bar AC Ampacity,
Without Sun (55.0% Conductivity)
Table B3 Aluminium Tubular Bus-Schedule 40 AC Ampacity
(53.0% Conductivity)
Table B4 Aluminium Tubular Bus-Schedule 80 AC Ampacity
(53.0% Conductivity)
Table B5 Single Aluminum Angle Bus AC Ampacity
(55.0% Conductivity)
Table B6 Double Aluminum Angle Bus AC Ampacity
(55.0% Conductivity)
Table B7 Aluminum Integral Web Channel Bus AC Ampacity
(55.0% Conductivity)
Table B8 Single Copper Rectangular Bar AC Ampacity, With
Sun (99.0% Conductivity)
Table B9 Single Copper Rectangular Bar AC Ampacity, Without
Sun (99.0% Conductivity)
Table B10 Copper Tubular Bus-Schedule 40 AC Ampacity
(99.0% Conductivity)
Table B11 Copper Tubular Bus-Schedule 80 AC Ampacity
(99.0% Conductivity)
Table B12 Double Copper Channel Bus AC Ampacity
(99.0% Conductivity)
Table D1 Standard Barometric Pressure (for Various Altitudes
Above Sea Level)